 ## Loops

We can use loops when we want to execute a part of code a certain number of times.

Here's an example:

``````for (initializing_variable; checking_condition; changing_variable_value)
{
//instructions to perform
}``````

This example, for comparison purposes, shows two ways of printing ten numbers. It's obvious that loops greatly reduce the number of lines in the code: from ten we now have just two!

Look at the parenthesis in the first line of the loop:

• int i = 1

A variable with the initial value of 1 was declared because we want to display the numbers from one (if you want to start from ten, it's enough to write int i = 10 in the same place).

You can name your variable any way you want but by convention it is 'i'” : you will for sure keep seeing it while reading about loops.

• i <= 10

Next, there is a condition check: in our case we check if the „i” variable is less or equal 10 (because we want to print numbers including ten).

•  i++

We change the value of the variable. '++' is an increment operator: it makes the value bigger by one. In the same place we could write the full operation: i = i + 1; it would also be correct. The effect would remain the same. But usually the shorthand is used.

Next, between the curly brackets, we write the instruction to be executed: we will print the 'i' variable incremented by one up to 10.

Declare a range from 117 to 143 and print all the numbers in it.

You can also count backwards. In that case the contents of the parentheses in the 'for' loop changes slightly: you enter the value to start from and where the loop must stop working. To illustrate it, code a New Year countdown: from 10 to 1 and then display the "Happy New Year!" message.

Example of the loop counting down::

for (int i = 20; i > 9; i--)

The countdown starts from 20. We count until 'i' is greater than 9 (that is, to 10), by decrementing the value of 'i' by one (similarly to how i++ was incrementing by one).